Translucent edge for instruments



a translucent edge showing the cavity or slot fori-ned iii-thc vertical side ofthe edge;

Fig. 5 is a. plan View of the fragment of an instrument showing the substantially rectangular cavities formed in spa-'Jed relation 4to each other on the face of the instrument;

Fig.- G is a plan rien' of a fagn-ient of an instrument showing circular apertures formed adjacent to the 'edge of the instri1 ment;

Fig. 7 is a modified form of the slot or rarity formed inthe side of the edge of an instrument; Y

Fig. S is a sectional vienv taken on the line S`8 of Fig. 1, -showing the slot as haring a substantially semi-circular cross section g' Fig. 9 is a fragmentary 'sectional rien` of aninstrulnent shoving an aperture formed adjacent the edge, thereof; l

Fig. 10 is a fragmentary sectional View of an instrument showing an aperture with :i inclined side formed adjacent the edge thereof; l Y i F 11 is a fragmentary sectional View of an instrument showing `the cross sectional outline of a slot or indentation formed adjaecut the edge of an instrument;

Fig. 12 illustrates a modified form of Ithe slot or indentation 4cross section;

Fig. 13 illustrates the shape of a slot for ditlusing the light; and

Figlei illustrates the shape of a slot. concentrating-the light rays.

in carryingV ont my invention I inalie in.' oan ins riunent in the illustration in 1 iiidieatalasilimdnated ruler (3,

.adjacent to an edge 7 of Which'and in parallelisni theren'i'tlnisnfornied an indentation or slot 8. The slot 8 is sc forrned that it receives the light rays ohliquely when the ruler G in in such a position that the edge i' thereof vould olist'ruet the iight rays. ln the present instance the slot or indentation is filled with air`Y while the whole inz-:tr-nn-:it is made of a trm'islncent material. ever, in sondev instances, it is possible that only the edge he made of translnevnt. mate`1'al`,'hu t theronstrnetion heretofore set forth would effectivelyprevent the casting of :1 -shadow upon the working surface by the edge 7.

As shon'n in Fig. S, the crossA section of the indentation S is Senn-circular so that it slightly diilnses the light raisA passing therethrough. The air isfof a {linie-rent density than any` transparent material from which the edge ofl an instrument maj,T bemade, therefore :r refraction occurs: in other Words,

the dire'tion of'a ray oflightwill he changed whenit enters opliquely a medium of (.ii'ferent density than the air through which i'tf has previously moved. The slot or indentation S is so spaced from the edge that the change of direction fill cause the rays of be of any ofthe forms hereinafter set forth so as to cause the said change of direction of the rays of light and illuminate the 'Working i surface immediately adjacent to the edge 1l.

In the case of instruments which are pi'ovided-With graduatioi'is, the slots or indentations may he formed on the side on Whieh the graduation marks are disposed, but it is preferable to have the indentations on the smooth, unmarked' side of the instrument so that. the' graduationsmay' be disposed directly upon the Working surface which will allow more accurate use of said instrument. A triangle 13, shown in Fig?.- 3, isprovided at eaeh of its ruling.r edges l; with indentations or slots 1G, which receive the rays ofA light obliqnely when the resptetive edge is turned away from the source of light. T he indentations 1G raus-e the rhangeof direction of assume various forms in accordance with the the light rays in the' manner heretofore set In some instaneesit nur); he desirable and :il-lonahle to forni the air pocket' or .Clotin the vertical. side-of the respective edge of the in.'- struinent. .In that caffe the .shape of slot may 95 the slot l" is curved as at 1S. While the lower side 19 of the slot. l? leads tothe working :airfaee so that the light is directed there- Upon. In Fig. 'i'. a substantially lil-shaped slot. 521 is formedon a rc1-'tical side of the instrument The apertnr'e or slot for the diffusion of the light rays may be formed with bridges therebetween or in, sections as shown vin Fig.

and in Fig. G. In Fig. 5 suhsta'ntially rectangular apertures 23 are formed with an in-l clined side Qi adjacent. theicdge :2G of the i-n-strinnent so that the inclined side Q4 receives the rays of light ohliqnely. The aper-A tnres'?) are Separatedfrznn each other in.'

'bridges Qi'. This een-sanction may beV adm5 of indeutations or slots so as to provide a 125 stratum of different density adjacent to the edge of the instrument. T he aperture 29 has vertical sides,A while one side-of the aperture' 3l is formed on an incline so. as to receive and,

reflect the light Arays in .slightlydiferent 13o manner in accordance with the instrument with wh-iclithey are used. 5

The cross sectional shape ofthe indentations or slots S, l2 or 16, maybe adapted to different. conditions so as to 'merely cause a refraction `or to diffu-se or concentrate the lightat certain points.' In Fig. 11 the indem tation 32 formed on the face of theixrstru-` ment is suitably spaced from the edf fe'tl1ere of'and'a side 33 of the indentation 3:2 is parallel with the edge, while the bottoni 34 of the indentationis formed on an incline. The

l indent-ation 36 in Fig. 12 has both sides thereof formed at an anglcso `that the light rays are received at a dilferent angle thanin' the other indentations heretofore set forth.

The slot or indentation 37 illustrated in Fig. 1 3 terminates in a concave curved side 3S which lnot onlyY receives the rays of light obliquely but it also causes a diffusion of the rays oflight. The indentation or slot 39 on the contrary, terminates in a convex curved side 4l adjacent to the edgeef the instrument thereby conc'entratinf,r the light rays on the desired points. rIhis last mentioned forni of the slot or indentation is .illustrated in Fig. 14. i

It is apparent that the slot or limlentation (ir-aperture formed atl-jacent to the edge Vof an instrument may be of a variety of shapes in accordance with the intensity oi.E the illu-mination required.

'heretofore described, aslot or an indentatioii,

lVliile 'in the illustration or otherwise held in said cavities to accomplish the purposes of the invention.

lt is also to be noted that while for the purpose of 'illustration l have shown the formation of translucent edges upon a scale, a preti-actor, and va triangle, such translucent edges`1nay be `formed ou any other type of instruments in the use of which'a certain degrec of-accuracy is essential. Suchen instrnnient may be a compass, the edges of the pointers or needles of which may be .formed in the manner heretofore setorth so as to facilitate the reading of the compassrcgardless'of the location of the source of light iiluniinating the plane thereof. There are numerous engineering and other type of'instru'inents in the vuse of which the edges when tdisposed in a certain nay relatiyely to the source of light, cast a shadoyv upon the work y ing plane or surface whereby accurate Work is I claim .and desire to secure by Letters Pat-v ent is:

l. In measuring and geometrical instruments, a transparent border and means oper atirely related'to the border to change the direction of the lightrays4 passing to' said border so as to direct the light rays to illumi nate a surface Von which the instrument is used; adjacent said border.

22. In a measuring orgcometrical instrument', a translucent 'body forming an operative edge of said instrument and a second translucent body disposed adjacent the Said edge,4 the said translucent bodies lieing' of different density to change'tlie direct-ion of the light ,rays "passing therethru so as to direct the `rays onto a surface on which the instrument is used. y

3. ln a measuring or geometrical instrunient, a translucent. body forming an operative `edge of said instrument and` a second translucent, body disposed adjacentthe said edge so as to directional-ily transmit the rays of light entering the same obliqucly, the said' ltranslucent bodies 'being of different density to change the direction of the light rays passing therethru so as to direct the rays onto a surface on which the instru-ment is used.

4. In a measuring or geometrica-l instrument, a translucent body forming a border -of'said instrument, said instrument lia-'ving a -carity'forined inoperative relation to tdie said border to change the direction of the rays of light toward 'said border 'because the illux-nination of a Working surface adjacent said border.

5. 'In a ineasurii-ig or geometrical insiru nient. a translucent bod)v forming a border of said instrument, said instruir-'lent llavingpa.v

cavity formed in operatixerelation tothe said lau-der and a translucent body of a densitydifferent. from that of the translucent border filling said cavity to change the direction 'of the -rays ofilight toward said bor;- dcr to canse the illumination of a Working surface adjacent said border.

6. In a measuring, or geometrical instrud ment, av .traJ-isliiccnt body forming a portion of said instrument adjacent to a -surface on n'hi ch the instrument is used; anothertranslucent` body disposed in operative 'relation to said first portion to direct the rays oil-ight therethru so as to illuminate said surface adjacent the-said tirst mentioned. p0rtlon.

7. In a measuring.,r or geoinctx'ical instru, ment, a translucent body forming an ledge of 1an l theinstrmncnt adj: cent :1 'surface-'on which the ust-fument is uned, 'said misti-fument hav `ing u cavity formed therein in;operative -relation to sind edge to' vreceive the z ars of' light nbl'iqucly and to; directioiially transmit, the

' .same toltlze edge; the ratio ofthe-difference in the density of said translucent body and of the Yair filling the said cavity being such :is to cause the refraction o'fithe light rays so` :is to directt-he -same upon the said surface adjacent to the said edge.

8. In a measuring or geometrical instrumenta translucent working edge on the -nsii-inhalt to be placed ,ons surf-ace on which l' the' irihtrument is fused 4and a cavity omed m 'operative relation to the sind ed e being l adapted to change the direction of t e light rays to .direct the same f ln'u said edge onto thesaid surface.

In a meiisuring'or geo'iiileltrical inst-rument a translucent working. edgeon the instriimelit to be placed on @surface -Gn'wli'ieh the instrument is 115ml' :md :1 cat-ity fOr-med iu operative. rel-ation to the said edge being adapted to change the direction olf the light l rays to cli-rccttlie same thru said eil-ge Onto the said surface. the cavity coopera-ting with the odge in such manner `:is to direct the light rays onto the .Quid surface in the' immediate 'proximity of the edge.

10. I-n a measuring er geometrical instru :ment a translucent `1Working edge G11-the instrument to be placed on :i surface on "which the instrument-is used and afeavity formed in operative' relation to the .si-:iid edge being uda-ptecl'to change' the' direction ofthe light rays to direct .the same-thru Vsaid edge'o'iito lthe sni'd su'rfsice; 'and n trm-isluceut iller--in saidA c nity having a den-sity d'izilcreiiit from that. of the ti-anslucentve'dgei In testimony whceof, I have lieten-nto s'et I niv-hand at San Francisco, California, this lili .any of Marh,19;29.

LEOPOLDM. KARNASCH. 

